With the continuous decrease in both critical dimension (CD) and pitch in “193 nm immersion lithography,” the use of a hardmask in certain layers of integrated circuit (IC) fabrication has become popular, owing to the excellent etch selectivity of the hardmask materials. Among the different hardmask approaches in recent years, metal hardmasks, such as TiN hardmask, are applied, using chemical vapor deposition (CVD), onto a processed wafer. Amorphous carbon hardmask, applied through either CVD or a spin-on technique, and silicon hardmask (or silicon antireflective coating or SiARC) are among the conventional technologies in IC fabrication. A spin-on, mixed metal hardmask (SOMMH) is now gaining its attraction in the IC industry, in part due to an attempt to replace the CVD metal hardmask for cost reduction and for simplification of fabrication processes. From a fabrication point of view, SOMMH is also believed to be able to replace SiARC in an IC fabrication scheme, especially when the substrate, to which patterns are to be transferred, is a silicon oxide dielectric material.
Hybrid metal (or organometal) nano-particles have gained their popularity in recent years. These organo metal nano-particles are used in polymer matrices for achieving certain physical/chemical properties, including increased refractive index and enhanced thermal stability. In these applications, a silsesquioxane-titanate hybrid polymer system for anti-reflective coating was first discussed by Chen, as early as in 2004 (see Chen et al., Material Chemistry and Physics, 83 (2004), 71-77). Non-bonded titanates in silsesquioxane matrix are described in U.S. Pat. No. 5,100,503. A silsesquioxane matrix bonded to titanates with sizes less than, or equal to, 5 nm are disclosed in WO 2007/053396. However, there remains a need for new hardmask compositions that can be used to form a SOMMH film with a high cross-link density and with excellent solvent resistance. These needs and others have been met by the following invention.